The present disclosure generally relates to an electrical generator or motor for converting rotational input energy into electrical output energy. Specifically, the present disclosure relates to a magnetically geared generator or motor including a magnetic gear unit combined with an electrical generator or motor.
In ship propulsion systems and wind energy turbines, e.g., a prime mover drives the propeller or wind drives the rotor, respectively, at variable speeds via a mechanical shaft such that rotational energy is input. The rotational energy is converted into electrical energy using an electrical generator which supplies an electrical frequency to an electrical distribution network of the ship or the wind turbine, respectively. Typical rotation speeds of wind turbine rotors, e.g., are in the order of 15 rpm such that a mechanical gear box has to be provided in order to obtain an output rotational frequency of 1500 rpm which is required by electrical machines to yield an electrical output frequency of 50 Hz.
In such an arrangement, a mechanical gearing is required in order to provide a sufficient rotational frequency for conventional electrical generators. Furthermore, the electrical output frequency should be constant even if the mechanical rotational input frequency is varied.
Especially for wind turbines mechanical gear boxes have to operate at a very high rotational torque in the order of Mega-Newton meters (MNm). Thus, a mechanical gear box may have a weight of up to 100 tons which has to be accommodated in a nacelle of a wind turbine high above ground.